1. Field of the Invention:
This invention relates to an oven provided with oxygen concentration controls, and more particularly to an oven provided with oxygen concentration controls and used to subject, for example, a rubber or plastic material or a product thereof to a heat aging test.
2. Description of the Prior Art
In general, during a heat aging test for a rubber or plastic material or a product thereof, a predetermined quantity per hour of the air in the test oven is replaced by the outside air, whereby the test is conducted as the ventilation of the test oven is properly controlled.
The regulating of the ventilation of the test oven is done by introducing and discharging a predetermined quantity, which corresponds to a predetermined frequency of ventilation, of air into and from the test oven on the basis of a change at least once per hour of such a quantity of air in the test oven that corresponds to the capacity thereof (according to JIS K 6301).
In a conventional heat aging test, the flow rate of the air introduced into the test oven and that of the air discharged therefrom are regulated but the testing of a sample is carried out actually irrespective of a decrease and variation of oxygen concentration occurring due to the absorption of oxygen by the sample being tested.
In such an oven, the aging of a rubber or plastic material is promoted by the oxygen in addition to the effect of the heat. Namely, when a decrease and variation of the oxygen concentration occurs in the test oven due to the number and oxygen absorption rate of the sample, the results of the test are influenced thereby greatly.
Therefore, if the oxygen concentration is not controlled during a test, the accuracy of the test decreases, and test results having reproducibility cannot be obtained. According to the conventional techniques of this kind, it is impossible to control the oxygen concentration in such a test oven.